Assessing which approach makes sense for your DC

Transcription

1 W H I T E P A P E R Free-standing mezzanines and rack-based mezzanines:? Assessing which approach makes sense for your DC M anaging inventory and fulfilling orders in today s omni-channel environment requires efficient systems for storing goods and smart use of vertical space in distribution centers (DCs). Today s DCs also call for sufficient clear space for the picking and packing involved in ecommerce fulfillment. Think of it this way: omnichannel fulfillment the trend toward DCs having to fulfill orders for multiple selling channels not only is causing companies to rethink their rack and storage systems, but also how to create space for value-added picking and packing activity. These needs can be mapped back to a common question that often arises when companies consider mezzanine solutions: What is the best route to take for my facility, a rack-supported mezzanine, or a free-standing mezzanine structure?

2 The operative word here is my, since which route to take for providing storage and space for value-added work will depend on what the needs are at a particular DC. In this white paper, we will discuss these needs, as well as the characteristics of rack supported mezzanines and those of free-standing mezzanine systems. A key question to consider is what will the mezzanine be used for primarily? If it s for storage and picking, you re probably going to lean towards a racksupported system. Paul Neal, vice president, UNARCO Material Handling Each approach has its place and its strengths, says John Moore, vice president of marketing for Cubic Designs, a manufacturer and provider of custom, free-standing mezzanine systems. It s not really a question of one approach being better than the other; it s more about what the need is and what the application will be. By examining these application needs in more detail, as well as through insights from providers of rack systems, mezzanine systems, and a DC integrator firm, the strong suits of each approach will become more apparent as well as how the two approaches can be combined to support today s fulfillment trends. Think application Rack storage systems are relied on by DC operators to efficiently store goods at the pallet, case, and item levels. Multi-level rack systems can be configured to make use of the full cube height of the facility, and are strong enough to hold a work platform on the upper level. Rack systems consist of modules with regularly spaced supports that serve a dual purpose: 1) they efficiently store goods within the rack modules; and 2) they provide a support structure for a platform/mezzanine on top. A rack-supported system may also include relatively wide (10-foot wide is common) walkways on its intermediate levels, which may be used as access for picking, or to route conveyor. A free-standing mezzanine system has support columns that are much more widely spaced than a rack system. This design allows for plenty of free and clear space on the ground level as well as on intermediate levels. A free-standing mezzanine also can incorporate shelving or rack on each level, so it too can provide storage, though not at the same density level as a rack-supported structure. One doesn t have to look far from the central function of rack structure itself dense and efficient multi-level storage to understand the key attraction behind rack supported mezzanines, says Paul Neal, a vice president with UN- ARCO Material Handling, a pallet rack manufacturer with experience providing either rack supported or free standing mezzanines. A key question to consider is what will the mezzanine be used for primarily? says Neal. If it s for storage and picking, you re probably going to lean towards a rack-supported system. By doing so, he adds, the storage structure itself becomes the mezzanine structure. In effect you re killing two birds with one stone and getting a more economical system, adds Neal. On the other hand, if the primary purpose is to obtain additional floor space for offices, to hold material handling equipment, for light manufacturing, kitting, or other reasons that are not storage related, a free-standing mezzanine may be more attractive. The decision is driven by the overall intended use of the structure. 1

3 Matching mezzanine choices to strengths Strengths of free-standing mezzanine Open space at each level allows for many applications, from value added work to light storage or placement of equipment. Layout of what is on each level is highly adaptable, since shelving, tables, or can be moved with relative ease. More flexibility in the type of flooring & decking that can be used. Greater distances between spans equates to more free and clear space for applications. Can support high loads such as concrete flooring or heavy equipment. Strengths of rack-supported mezzanine Well suited to storage-intensive needs since storage structure also can support a top level platform or mezzanine Layout of rack module levels can t be easily adapted without reconfiguring rack structure. Weight of the structure is evenly distributed on the floor load because rack modules have many evenly spaced columns. Economical when high density storage is the clear priority and need for future adaptability is low. 2 While it would be possible to have a free-standing mezzanine with rack located underneath, there are complications to this approach, notes Jim Crews, a professional engineer with UNARCO. If you build a free-standing mezzanine system and then try to place rack or shelving underneath, not only do you have to miss the building columns when you configure the rack, but you also have to miss the mezzanine columns, says Crews. It s complicated because you have three structural systems instead of two. That s why most customers, if they have storage as the main intent, will go the rack supported route, because they ll just have one structural system they have to buy, and can still have an open level on top. When the main objective is dense, multi-level storage with some free space up top, Moore agrees that it s hard to beat the rack-supported approach. For customers looking for high-density storage, essentially you are leveraging the same steel for the rack storage to support a mezzanine on the top level, says Moore. So there is some materials savings there when the driving factor is high-density storage. The need for flexibility The big advantage of a free-standing mezzanine is versatility, according to Julie Vargo, systems sales consultant with VARGO Companies, a Hilliard, Ohiobased organization that offers a full range of design and process improvement services for DCs, including mezzanines. While Vargo notes that both rack-supported mezzanines and free-standing mezzanines have their place in DCs, free-standing mezzanines are very versatile. For one thing, a free-standing mezzanine allows for open space at each level, including the ground level, notes Vargo. This makes a free-standing mezzanine the most practical approach for spanning over a ground floor production area in which space is needed for equipment and work in process (WIP) activities. If you needed space over a busy production floor, you would almost certainly go with a free-standing mezzanine, says Vargo. Another aspect of versatility with a free-standing mezzanine is that it can hold shelving or pallet rack, which can be moved around with relative ease, says Vargo. You have a lot of versatility with a free-standing platform or mezzanine levels, says Vargo. You can put free-standing shelving on a platform, and underneath you might want to have an area for kitting with tables and work in process. A rack-supported approach tends to be most suitable and cost effective when maximum storage capacity is needed at multiple levels, since in these designs, the storage modules double as support for a mezzanine on top. This can be a very cost efficient design, says Vargo, especially for pick modules which are three floors or higher. A free-standing mezzanine or platform can also be configured to nearly any

4 Free standing mezzanines and platforms are very versatile, it s like the creativity you have with a toy Erector set in that you can configure the support columns and floors that you need and have a platform for nearly any use. Julie Vargo, systems sales consultant, VARGO Companies dimension. At some facilities, VARGO uses narrow, free-standing platforms to provide maintenance personnel access to raised sections of conveyors or other material handling systems. A free-standing mezzanine can also be very robust, with supports capable of holding a poured concrete floor, adds Vargo, which would not be a suitable floor for a rack-based structure. Free standing mezzanines and platforms are very versatile, Vargo says. It s like the creativity you have with a toy Erector set in that you can configure the support columns and floors that you need and have a platform for nearly any use. UNARCO s Neal agrees custom mezzanines are versatile. A free-standing system offers more flexibility in terms of the lengths of the spans and size of supporting beams. Additionally, a multi-level, free-standing mezzanine system can have open mezzanine space on each level, which can be used for shelving, office space, equipment storage, or for activities such as kitting that require free space. To sum up, says Moore, free-standing mezzanines offer versatility in various ways, from the wide variety of floors and decking that can be used, to the simple fact that the free space at each level can be used in many conceivable ways from space for value-added work, for offices, conveyor, or for smaller storage systems such as shelving. A free-standing mezzanine is also highly adaptable to future needs, says Moore, in that if you want to change the placement of shelving, tables, equipment, or racks on its various levels, it s relatively easy to move gear or shelving around. By contrast, with a rack supported structure, a top level mezzanine offers flexibility, but lower supporting levels consisting of rack modules would have to be taken apart and reconfigured to significantly change the applications on the lower levels. A free-standing mezzanine can handle significant changes to layouts on its level, where as a rack system is more sensitive to change, says Moore. So you have to consider your need for future adaptability. Combining the two It s is not uncommon to combine the two approaches a rack supported mezzanine adjacent to a free-standing mezzanine with the work processes on both complementing each other, says Neal. For example, some customers have asked for a rack-supported mezzanine to be built next to a free-standing mezzanine, with the lower levels of the rack system providing storage, while the free-standing structure can be used to hold conveyors, sorters, or other equipment, or as free space for picking or kitting. We re sometimes asked to match floor elevations so that personnel can walk from the free standing mezzanine right onto the rack supported structure, Neal says. Combining the two approaches is done frequently on projects. Companies often combine rack systems and free-standing mezzanines, agrees Vargo, using multi-level, rack-based pick modules for storage and access to 3

5 goods, with a free-standing structure next to it to support equipment or picking activities. At one project for a major e-commerce company, Vargo says that a free-standing platform was added next to a multi-level, rack-based structure, with the free-standing platform housing a vertical reciprocating lift (VRC). The VRC is used to move and replenish goods to the multi-level pick module locations. Moore also sees companies who combine racks and mezzanines to function cohesively as an infrastructure for storage and fulfillment. With a multi-level rack supported system you have the need for high density storage covered, and can include some open areas, and when you combine that with an adjacent free-standing mezzanine, you have a larger open area that can be used for activities like kitting or packing items. Storage centric vs. versatility Since rack-supported mezzanines and free standing mezzanines each work well in certain situations, it s not accurate to think of one approach versus the other, but rather, to determine what is the driving application need, concludes Moore. When the need is centered on high density, multi-level storage, that s where the rack-based approach will follow, says Moore. Rack-supported mezzanine designs, Neal agrees, tend to be most suitable when the main intent behind the project is to add storage. Free-standing mezzanines are more suitable when the main intent is to add floor space or to maintain maximum flexibility. As Neal sums up, Generally speaking, the more the space involves storage, the more people are going to gravitate towards a rack-supported mezzanine because it s more cost effective and functional to provide one structure for both. M